In flipping through some transmission literature I found that the 71c is rated for a maximum of 255hp and the 72c for 380 hp. This seems like a massive difference for transmissions that use the same clutch assemblies. Can anyone tell me why the difference, or if they have modded a boat with the 71c to significantly more than 255 hp and what the long/ short term effects have been? I am curious as I have a 240 sc with the 351w motor and though I have not had a chance to run it yet I can only assume that I will want mo power, especially torque.
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04-03-2013, 07:43 AM
I'm not sure why the documentation says those numbers but the trans will handle a lot more then that. It might have something to do with NET and Gross HP ratings too. You could probably add 20% to any book printed after 1971.
The factory output on some of the older 351w is 285hp and that came with a 71.
04-03-2013, 08:20 AM
I also found this info.
General Information for Model 71C (10-17)
Ratings: Gasoline up to 310 HP @ 4200 RPM Ratings: Diesel up to 182 HP @ 3200 RPM Available Ratios: 1.00, 1.52, 1.91*, 2.10, 2.57, 2.91:1.00 Shaft Rotation output same as engine unless noted by asterisk (*) Approximate Dry Weight
(direct drive): 95 lb. (43.1 kg.) Approximate Dry Weight
(reduction) 145 lb. (65.8 kg.)
General Information for Model 72C (10-18)
Ratings: Gasoline up to 475 HP @ 4200 RPM Ratings: Diesel up to 274 HP @ 3200 RPM Available Ratios 1.00, 1.52, 1.91*, 2.10, 2.57, 2.91:1.00 Shaft Rotation output same as engine unless noted by asterisk (*) Approximate Dry Weight
(direct drive): 109 lb. (49.4 kg.) Approximate Dry Weight
(reduction) 153 lb. (69.4 kg.)